1. Field of the Invention
This invention pertains, in general, to the field of retractable covers or roofs for large structures, such as athletic stadiums. More specifically, the invention relates to an improved transport mechanism for such a structure that is more compact, reliable, stable, mechanically simple and inexpensive to construct than comparable mechanisms heretofore known.
2. Description of the Related Technology
It is common these days for athletic stadiums to be constructed with retractable roofs, because this type of construction offers spectators the pleasure of being outdoors on nice days, while providing shelter when necessary against extreme temperatures and inclement weather conditions.
A number of factors must be taken into account in the design of a stadium that has a retractable roof. For instance, the forces created by the exertion of natural forces such as wind, rain snow and even earthquakes on such a large structure can be enormous, and the roof, the underlying stadium structure and the transport mechanism that is used to guide and move the roof between its retracted and operational positions must be engineered to withstand the worst possible confluence of such forces. In addition, for reasons that are both aesthetic and practical, it is desirable to make the structural elements of the roof and the transport mechanism to be as unobtrusive and as space-efficient as possible. It is desirable to make the roof structure and the transport mechanism to be as simple and maintenance-free as possible, and to be constructed so as to be able to open and close as quickly as possible.
Many cities in the United States and elsewhere are now using or building retractable proofed stadiums. The designs of the various stadiums are quite different, but there are a number of deficiencies that seem to be common to all of the designs that have been implemented thus far. For example, the transport mechanisms in most of the stadiums tend to be quite large, being as much as twenty to thirty feet in height. The transport mechanisms further tend to include a relatively small number of very large, heavily loaded wheels and bearings, and a small number of very large motors or actuators to drive the roof between the retracted and operational positions. The small number of large wheels exert very large concentrated loads onto the support structure, which requires the support structure to be heavily reinforced, adding to the cost and complexity of the stadium as a whole. The roof and transport mechanisms in existing designs further tend to be relatively heavy and inflexible, and often experience alignment problems during movement.
A need exists for an improved design for a stadium that has a retractable roof that is more compact, reliable, stable, mechanically simple and inexpensive to construct than comparable mechanisms heretofore known.
Accordingly, it is an object of the invention to provide an improved design for a stadium that has a retractable roof that is more compact, reliable, stable, mechanically simple and inexpensive to construct than comparable mechanisms heretofore known.
In order to achieve the above and other objects of the invention, a convertible large edifice, such as an athletic stadium, of the type that is equipped with a movable overhead shelter mechanism, includes, according to a first aspect of the invention, foundation structure; at least one overhead shelter assembly positioned above the foundation shelter; and guide and support means for supporting the overhead shelter assembly and guiding the overhead shelter assembly for movement with respect to the foundation structure, the guide and support means including at least one rail member that is secured to one of the foundation structure and the overhead shelter assembly; a plurality of independently suspended follower assemblies that are mounted to the other of the foundation structure and the overhead shelter assembly, each of the follower assemblies including a wheel member that is positioned in contact with the rail, and a resilient member that is interposed between the wheel member and the other of the foundation structure and the overhead shelter assembly whereby each of the wheel members is independently suspended with respect to the other wheel members.
According to a second aspect of the invention, a stadium that is adapted for open use during good weather as well as for covered use during poor weather includes foundation structure; a pair of movable end roof members that are movable between first, retracted positions and second, operational positions for covering first and second end areas, respectively, of the stadium; and a center roof member that is movable between a retracted position and an operational position for covering a center area of the stadium; and wherein at least one of the center roof member and the two end roof members are supported for movement between one of the retracted positions and one of the operational positions by a guide and support means that includes at least one rail member that is secured to the foundation structure; and a plurality of independently suspended follower assemblies that are mounted to the respective roof member, each of the follower assemblies including a wheel member that is positioned in contact with the rail, and a resilient member that is interposed between the wheel member and the other of the foundation structure and the overhead shelter assembly, whereby each of the wheel members is independently suspended with respect to the other wheel members.
These and various other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.